I have B:M and have been playing B:G on TTS for the aforementioned session report. I'd say they're about as different in gameplay as it's possible for games to be. They share a similar appreciation for fairly rigorous science, and a penchant for clever abstraction of complex concepts. And there's a superficial similarity between the predator/prey relationship in Megafauna and the host/parasite relationship in Genesis, but they play radically different. Genesis really is a game about parasitism and hostile cooperation... with dice. Megafauna is about variation and spreading to avoid environmental culls.. without dice. I think they're both great but quite different solo games.